1. Field of the Invention
The invention relates to the field of circuits and microsystems having one or more piezoelectric and/or acoustic resonators.
2. Description of the Related Art
Photodetectors may be produced in CCD (Charge Coupled Device) technology or in MOS (Metal Oxide Semiconductor) technology. A photodetector in MOS technology is described for example in document U.S. Pat. No. 5,625,210.
Unlike CCD-type photodetectors which may be supplied by an electrical voltage source whose voltage may exceed 10 volts, MOS-type photodetectors cannot be supplied by an electrical voltage source whose voltage exceeds about 3.3 volts. As a result, the useful signal from a MOS photodetector is much weaker than that from a CCD photodetector. Consequently, a MOS photodetector can make a significant distinction between different light fluxes only if the intensity of these fluxes lies within a given interval, called the linear detection interval. Beyond this interval, the electrical signal delivered by the photodetector is no longer proportional to the luminous flux, and undesirable phenomena occur such as, in particular, blooming and/or an error in transferring electrical charge into the photodetector.
Another consequence of the lower electrical voltages used in a MOS photodetector compared with those in a CCD photodetector is the presence of residual electrical charge that is not transferred from the photodiode. This residual electrical charge remains in the photodiode, despite the process for transferring electrical charge from the photodiode to the sensing node being controlled.
Accordingly, there exists a need for overcoming the disadvantages of the prior art as discussed above.